Coffee sunscreen? How caffeine prevents skin cancer

Caffeine might become the newest weapon in skin damage prevention because it helps kill off the cells damaged by UV radiation before they become cancerous.

Forget cocoa butter…

Turns out, lathering on caffeine could guard against skin cancers. And scientists have figured out what’s going on at the molecular level.

Previous studies, some of which involved feeding caffeinated water to mice, have shown that coffee drinking is associated with a decreased risk of nonmelanoma skin cancer, but how and why was unknown.

We know that ultraviolet light damages the DNA in skin cells. Caffeine blocks a large protein called ATR (short for ataxia telangiectasia and Rad3-related enzyme). The Scientist explains:

[ATR] senses incomplete DNA replication – often a result of DNA damage – and signals the cell to not divide. By inhibiting ATR activity, caffeine could make cells more likely to die in response to UV damage, preventing damaged cells from ever becoming cancerous.

So the team – led by Allan Conney from Rutgers and Paul Nghiem from the University of Washington, Seattle – genetically modified some mice to reduce the function of ATR in their skin.

  1. When exposed to UV light, tumors developed 3 weeks later in the modified mice than in the regular, unmodified mice.
  2. After 19 weeks of UV light exposure, the modified mice had 69% fewer tumors and 4 times fewer invasive tumors than in unmodified mice.
  3. But after 34 weeks of continued UV irradiation, all of the mice had developed tumors.

The findings suggest that caffeine’s protective effect against UV damage is due to ATR inhibition during the pre-cancerous stage, before UV-induced skin cancers fully develop.

There are more than one million new cases of skin cancer each year in the US, according to the National Cancer Institute.

Caffeine has an added benefit of directly absorbing damaging UV light. “Therefore adding it to sunscreens may make sense for two reasons,” Nghiem says. “It’s directly a sunscreen, and completely independently, it has this effect on ATR.”

The study was published today in the Proceedings of the National Academy of Sciences.

Image by jppi via morgueFile

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